Reduction of metals to powdered or granular form



June 18, 1946. X L. H. PADDLE 2,465,141

REDUCTION OF METALS TO 'POWDERED OR GRANULAR FORM Filed April 6, 1945 Patented June 1 REDUCTION OF METALS T POWDERED OR GRANULAR FORM Leslie Harold Paddle, St. Paul's Cray, England Application April 6, 1943, Serial N0."482,010

In Great Britain April 30, 1942 a 1 Claim.

This invention relates to the reduction of metals to powdered or granular form and comprises i a method of and means whereby this desideratum can be accomplished. The invention is particularly applicable for the powdering, granulating, or atomising of metals or alloys of high melting point and metals of great ductility which are difficult to pulverise mechanicallyr The invention consists broadly of an improved process for reducing metals to powdered or granular iorm according to which a stream ofthe metal in molten condition is caused to pass in contact with a blast of gaseous fluid.

More specifically the invention comprises the use in the process of a gaseous fluid which is neutral or inert where itis desired that the powder and granules shall remain of the same chemical composition as the metal being treated or of such a character as will combine with the metal to form powder orgranules of a compound or the metal and the gaseous fluid.

I The invention further contemplates the use,

in some cases, of hydrogen or other reducing gas.

The invention further comprises'the apparatus by means of which the process can be carried out, an example of which is illustratedin the accompanying diagrammatic drawing.

In carrying out the invention the metal to be' be a ring of Jets which may be so directedas to give the gas stream a whirling motion. The

t Venturi nozzle being 01' refractory material will serve to maintain the temperature or the metal and the Venturi action will increase the atomising eflect of the gas. Y

The metal reduced to powder or granular form by the action of the blast passes from the Venturi nozzle and is deposited in the receiver 8 which may contain a cooling fluid whiclrmay have non-oxidizing or other protective properties, from which it can be removed from time to time. The numeral 1 designates a pump by which the gaseous fluid is circulated. In the case where a neutral gas is employed the gas is introduced through the pipe 8 under control of the valve 8 v and when suiflcient gas has been introduced into the system the valve 8 is closed and the gaseou- 2 tained in the system circulated continuously, a filter and purifier i0 being preferably employed to prevent any particles getting into and impairing the action of the pump, and to remove gase- 5 ous impurities. The gas passes to the nozzle 5 by way 0! the pipe II. -A branch I2 is led to the top of the crucible I so that gas pressure can be utilised when desired to assist in discharging the molten metal through the orifice 3.

1o In cases where a reacting gas such as air or oxygen is used in the process and combines with the metal to form powder or granules of a metallic compound of the metal and the gas, the gas will, of course, need to be continuously supplied is to the pump inlet pipe! and the valve 9 will be lettopen Where the metal being treated is an alloy containing ferrous metal'and it is desired to'separate of! the errous constituent;-a-magnetic sysgo tem can bemployed such as-"indicated in'the drawing wherein it indicatesQone pole of an electro-magnet ene gised by a coil ll, the other pole of the magnet eing constituted by thering I 5 surrounding thelvertical stack l6 of the appaguratusn I g It is to be-understood that the foregoing speciflc description is given by way at example only, because except for the essential condition or sub- Jectihg a stream of molten metal to a blast of gaseous fluid, which must be observed; the conditions and precise requirements may ary considerably. In some cases for example it may be desirable that the gaseous fluid should be cooled instead of preheated and in cases of preheating it may in some cases be advantageous to raise thetemperature oi the gas above the melting point or the metal. Moreover, by providing the vertical stack IQ with varying temperature zones, either by applying suitably disposed heating or cooling elements. the falling powder or granules may be subjected to special heat treatment in their passage to the receiver 6.

;'Ihese heating or cooling elements may encircle the vertical stack II which may be suitably restricted in area in order to maintain the temperature in any particular zone substantially regular and homogeneous. It is to be noted that an important advantage of the methodhereinbeiore described lies in the complete fusion of the metal or alloy before contact" with the gaseous fluid, thus eliminating any possibility-oi the metal being subjected to the action oi'the gaseous stream while in a semifluid state resulting in irregularity in the size and shape of the particles as would occur, for

r l l 4 an elongated closed chamber, means including a nozzle at one end of said chamber for injecting a solid stream of molten metal into said chamber. means including a nozzle tor impinging a stream oi gas against said stream oi metal, a Venturi nozzle within said chamber and spaced apart from the first and second named nozzles and alined therewith, means at the other end oi said chamber for separating subdivided metal from las 10 and means for returning the separated gas to the second named nozzle.

LESLIE HAROLD PADDLE. 

